Method of manufacturing a magnetoresistive random access memory device

Abstract

In a method of manufacturing a magnetoresistive random access memory, a memory structure may be formed on a substrate. The memory structure may include a lower electrode, a magnetic tunnel junction (MTJ) structure, and an upper electrode sequentially stacked. A protection layer including silicon nitride may be formed to cover a surface of the memory structure. The protection layer may be formed by a chemical vapor deposition process using plasma and introducing deposition gases including a silicon source gas, a nitrogen source gas containing no hydrogen and a dissociation gas. Damages of the MTJ structure may be decreased during forming the protection layer. Thus, the MRAM may have improved characteristics.

What is claimed is: 
     
       1. A method of manufacturing a magnetoresistive random access memory, the method comprising:
 forming a memory structure on a substrate, the memory structure including a lower electrode, a magnetic tunnel junction (MTJ) structure, and an upper electrode sequentially stacked on the substrate; and 
 forming a protection layer covering a surface of the memory structure, the protection layer including silicon nitride, 
 wherein the forming the protection layer includes a chemical vapor deposition process, the chemical vapor deposition process including
 using a plasma, and 
 introducing deposition gases including a silicon source gas, a nitrogen source gas containing no hydrogen, and a dissociation gas, the dissociation gas being introduced at a flow rate of 50% to 90% of the deposition gases. 
 
 
     
     
       2. The method of  claim 1 , wherein the using the plasma includes applying a high frequency R.F. power in 13.56 MHz band. 
     
     
       3. The method of  claim 1 , wherein the using the plasma includes applying an R.F. power in pulses. 
     
     
       4. The method of  claim 3 , wherein a duty cycle of the plasma is in a range of about 1% to about 10%. 
     
     
       5. The method of  claim 1 , wherein the nitrogen source gas includes N 2 . 
     
     
       6. The method of  claim 1 , wherein the dissociation gas includes an inert gas. 
     
     
       7. The method of  claim 1 , wherein the silicon source gas includes SiH 4 , Si 2 H 6 , Si 3 H 8 , or Si 2 H 6 . 
     
     
       8. The method of  claim 1 , wherein the forming the protection layer further comprises:
 introducing the nitrogen source gas at a flow rate higher than a flow rate of the silicon source gas. 
 
     
     
       9. The method of  claim 8 , wherein the flow rate of the nitrogen source gas is in a range of about 3 times to about 100 times of the flow rate of the silicon source gas. 
     
     
       10. The method of  claim 1 , wherein the forming the protection layer further comprises:
 introducing the silicon source gas at a flow rate of about 0.1% to about 10% of the deposition gases, and 
 introducing the nitrogen source gas at a flow rate of about 8% to about 49% of the deposition gases. 
 
     
     
       11. The method of  claim 1 , wherein the forming the memory structure comprises:
 forming a lower electrode layer, an MTJ layer, and an upper electrode layer sequentially stacked on the substrate; and 
 etching portions of the upper electrode layer, the MTJ layer and the lower electrode layer to form the memory structure including the lower electrode, the MTJ structure and the upper electrode. 
 
     
     
       12. A method of manufacturing a magnetoresistive random access memory, the method comprising:
 forming a transistor on a substrate, the transistor including a gate, a first impurity region and a second impurity region; 
 forming a source line electrically connected to the first impurity region; 
 forming a memory structure including a lower electrode, a magnetic tunnel junction (MTJ) structure and an upper electrode sequentially stacked, the memory structure being electrically connected to the second impurity region; 
 forming a protection layer covering a surface of the memory structure, the protection layer including silicon nitride; and 
 forming a bit line on the memory structure, the bit line being electrically connected to the upper electrode of the memory structure, 
 wherein the forming the protection layer includes a chemical vapor deposition process including
 using a plasma, and 
 introducing deposition gases including a silicon source gas, a nitrogen source gas containing no hydrogen, and a dissociation gas the dissociation gas being introduced at a flow rate of 50% to 90% of the deposition gases. 
 
 
     
     
       13. The method of  claim 12 , wherein the using the plasma includes applying a high frequency R.F. power in 13.56 MHz band. 
     
     
       14. The method of  claim 12 , wherein the using the plasma includes applying an R.F. power in pulses. 
     
     
       15. The method of  claim 12 , wherein the nitrogen source gas includes N 2 . 
     
     
       16. A method of manufacturing a magnetoresistive random access memory, the method comprising:
 sequentially forming a lower electrode layer, a magnetic tunnel junction (MTJ) layer, and an upper electrode layer on a substrate; 
 etching portions of the upper electrode layer, the MTJ layer, and the lower electrode layer to form a memory structure, the memory structure including a lower electrode, an MTJ structure, and an upper electrode on the substrate; 
 loading the substrate into a deposition chamber; and 
 forming a protection layer covering a surface of the memory structure, the protection layer including silicon nitride, 
 wherein the forming the protection layer includes
 introducing deposition gases into the deposition chamber, the deposition gases including a silicon source gas, a nitrogen source gas containing no hydrogen, and a dissociation gas, the dissociation gas being introduced at a flow rate of 50% to 90% of the deposition gases introduced into the deposition chamber, and 
 periodically applying an R.F. power in a pulse to generate plasma. 
 
 
     
     
       17. The method of  claim 16 , wherein the R.F. power has a high frequency in a 13.56 MHz band. 
     
     
       18. The method of  claim 16 , wherein the nitrogen source gas includes N 2 .